U.S. patent number 9,893,327 [Application Number 14/379,531] was granted by the patent office on 2018-02-13 for electric storage apparatus.
This patent grant is currently assigned to TOYOTA JIDOSHA KABUSHIKI KAISHA. The grantee listed for this patent is Masaru Ishii, Masato Kamiya, Keiichiro Kobayashi, Taira Saito. Invention is credited to Masaru Ishii, Masato Kamiya, Keiichiro Kobayashi, Taira Saito.
United States Patent |
9,893,327 |
Kobayashi , et al. |
February 13, 2018 |
Electric storage apparatus
Abstract
An electric storage apparatus includes a plurality of electric
storage elements placed side by side along a predetermined
direction and a restraint plate placed between two of the electric
storage elements adjacent to each other in the predetermined
direction. The electric storage element has a power-generating
element performing charge and discharge and a case housing the
power-generating element. The restraint plate has protruding
portions which give a restraint force to the electric storage
element and form a space between the restraint plate and the
electric storage element. The power-generating element has a
positive electrode plate, a negative electrode plate, and a
separator placed between the positive electrode plate and the
negative electrode plate. The power-generating element includes a
reaction area where a chemical reaction associated with the charge
and discharge occurs. The plurality of protruding portions have a
first protruding portion in contact with a first area in the case
and a second protruding portion in contact with a second area in
the case. The first area in the case is opposite to the reaction
area, and the second area in the case is opposite to the area of
the power-generating element except the reaction area.
Inventors: |
Kobayashi; Keiichiro (Nissin,
JP), Saito; Taira (Miyoshi, JP), Ishii;
Masaru (Miyoshi, JP), Kamiya; Masato (Anjo,
JP) |
Applicant: |
Name |
City |
State |
Country |
Type |
Kobayashi; Keiichiro
Saito; Taira
Ishii; Masaru
Kamiya; Masato |
Nissin
Miyoshi
Miyoshi
Anjo |
N/A
N/A
N/A
N/A |
JP
JP
JP
JP |
|
|
Assignee: |
TOYOTA JIDOSHA KABUSHIKI KAISHA
(Toyota-shi, JP)
|
Family
ID: |
49005118 |
Appl.
No.: |
14/379,531 |
Filed: |
February 21, 2012 |
PCT
Filed: |
February 21, 2012 |
PCT No.: |
PCT/JP2012/001162 |
371(c)(1),(2),(4) Date: |
August 19, 2014 |
PCT
Pub. No.: |
WO2013/124889 |
PCT
Pub. Date: |
August 29, 2013 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20150056487 A1 |
Feb 26, 2015 |
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01M
10/0468 (20130101); H01M 50/20 (20210101); H01M
10/0472 (20130101); H01M 10/6556 (20150401); Y02E
60/10 (20130101); Y02P 70/50 (20151101) |
Current International
Class: |
H01M
10/6556 (20140101); H01M 2/10 (20060101); H01M
10/04 (20060101) |
Field of
Search: |
;429/120,156 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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|
|
|
|
|
100452482 |
|
Jan 2009 |
|
CN |
|
102171883 |
|
Aug 2011 |
|
CN |
|
2006-310309 |
|
Nov 2006 |
|
JP |
|
2008-078008 |
|
Apr 2008 |
|
JP |
|
2009-266413 |
|
Nov 2009 |
|
JP |
|
2010-097693 |
|
Apr 2010 |
|
JP |
|
2010-165597 |
|
Jul 2010 |
|
JP |
|
2010-287530 |
|
Dec 2010 |
|
JP |
|
Primary Examiner: Lee; James
Attorney, Agent or Firm: Andrews Kurth Kenyon LLP
Claims
The invention claimed is:
1. An electric storage apparatus comprising: a plurality of
electric storage elements placed side by side along a predetermined
direction, each of the plurality of electric storage elements
having a power-generating element for performing charge and
discharge and a case housing the power-generating element, the
power-generating element including a reaction area; and a restraint
plate having a plurality of protruding portions, the plurality of
protruding portions giving a restraint force to one of the
plurality of electric storage elements and being in contact with
the case adjacent to the restraint plate to form a space between
the restraint plate and one of the plurality of electric storage
elements, the restraint plate being placed between two of the
plurality of electric storage elements adjacent to each other in
the predetermined direction, wherein the power-generating element
has a positive electrode plate, a negative electrode plate, and a
separator placed between the positive electrode plate and the
negative electrode plate, and a chemical reaction associated with
the charge and discharge occurs in the reaction area, wherein the
reaction areas of a plurality of the power-generating elements are
misaligned in a lateral direction of each of the plurality of
electric storage elements orthogonal to the predetermined
direction, and the plurality of protruding portions each having: a
first protruding portion in contact with a first area of the case
adjacent to the restraint plate, the first area being an area where
all of the reaction areas of the plurality of electric storage
elements are overlapped with one another in the predetermined
direction; and a second protruding portion in contact with a second
area of the case adjacent to the restraint plate, the second area
opposite to an area of the power-generating element adjacent to the
restraint plate except the reaction area, the second area being not
opposite to all of the reaction areas of the plurality of electric
storage elements, wherein the plurality of electric storage
elements are not misaligned in the lateral direction orthogonal to
the predetermined direction.
2. The electric storage apparatus according to claim 1, wherein the
positive electrode plate has a positive electrode collector plate
and a positive electrode active material layer formed on the
positive electrode collector plate, the negative electrode plate
has a negative electrode collector plate and a negative electrode
active material layer formed on the negative electrode collector
plate, and the separator is larger in width than the positive
electrode active material layer and the negative electrode active
material layer.
3. The electric storage apparatus according to claim 2, wherein the
second protruding portion gives a restraint force to an edge of the
separator through the case.
4. The electric storage apparatus according to claim 1, wherein the
first protruding portion comprises a plurality of the first
protruding portions, and at least one of the plurality of first
protruding portions is placed along an edge of the first area.
5. The electric storage apparatus according to claim 1, wherein the
second protruding portion comprises a plurality of the second
protruding portions, and at least one of the plurality of second
protruding portions is placed along an edge of the second area.
6. The electric storage apparatus according to claim 1, wherein the
power-generating element is provided by winding the positive
electrode plate, the negative electrode plate, and the separator
around a predetermined axis.
7. The electric storage apparatus according to claim 6, wherein at
least one of the first protruding portion and the second protruding
portion extends in a direction orthogonal to a direction in which
the predetermined axis extends, in a plane including the first area
and the second area.
8. The electric storage apparatus according to claim 6, wherein a
length of the case in the direction in which the predetermined axis
extends is larger than a length of the case in the direction
orthogonal to the predetermined axis in the plane including the
first area and the second area.
9. The electric storage apparatus according to claim 1, further
comprising a pair of end plates placed at positions where the
plurality of electric storage elements are sandwiched in the
predetermined direction; and a coupling member extending in the
predetermined direction and fixed to the pair of end plates.
10. The electric storage apparatus according to claim 1, wherein
the space is a path in which a heat exchange medium for use in
adjusting a temperature of the electric storage element is moved.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
This is a national phase application based on the PCT International
Patent Application No. PCT/JP2012/001162 filed Feb. 21, 2012, the
entire contents of which are incorporated herein by reference.
TECHNICAL FIELD
The present invention relates to an electric storage apparatus
including a mechanism for giving a restraint force to a plurality
of electric storage elements arranged along one direction.
BACKGROUND ART
A battery stack may be provided by arranging a plurality of cells
along one direction. A restraint mechanism may be used to give a
restraint force to the plurality of cells. The restraint force
refers to a force which tightly holds the plurality of cells in the
direction of the arrangement of the plurality of cells.
Specifically, as described in Patent Document 1, a partitioning
plate is placed at a position adjacent to a cell, and a protruding
portion provided on the partitioning plate is brought into contact
with the cell to give a restraint force to the cell from the
partitioning plate. The protruding portion is used to form a space
between the cell and the partitioning plate for moving a heat
exchange medium used in adjusting the temperature of the cell.
PRIOR ART DOCUMENT
Patent Document
[Patent Document 1] Japanese Patent Laid-Open No. 2010-097693
DISCLOSURE OF THE INVENTION
Problems to be Solved by the Invention
In giving the restraint force to the cell, it is desirable to give
the restraint force evenly to the face of the cell which receives
the restraint force. The cell accommodates a power-generating
element capable of charge and discharge. In the configuration in
which the restraint force is simultaneously given to a plurality of
cells, the uniform restraint force needs to be given to the
power-generating elements of the plurality of cells. The uniform
restraint force needs to be given particularly to reaction areas of
the power-generating elements where charge and discharge are
performed.
The cells may have manufacturing variations. When the plurality of
cells are arranged, the cells may be misaligned. In view of the
manufacturing variations and the misalignment, the restraint force
is preferably given only to the area of the plurality of cells
where their power-generating elements (reaction areas) are placed
one on another in the direction of the arrangement of the cells.
This can result in equalized restraint forces applied to all the
reaction areas.
When the restraint force is given only to the areas where the
reaction areas are placed one on another, however, the restraint
force is applied only to part of the cell, and the restraint force
cannot be given to the entire face of the cell which receives the
restraint force. For maintaining the input/output performance of
the cell and the like, the restraint force is preferably given to
the entire cell rather than part of it.
Means for Solving the Problems
According to an aspect, the present invention provide an electric
storage apparatus including a plurality of electric storage
elements placed side by side along a predetermined direction and a
restraint plate placed between two of the electric storage elements
adjacent to each other in the predetermined direction. The electric
storage element has a power-generating element performing charge
and discharge and a case housing the power-generating element. The
restraint plate has protruding portions which give a restraint
force to the electric storage element and form a space between the
restraint plate and the electric storage element.
The power-generating element has a positive electrode plate, a
negative electrode plate, and a separator placed between the
positive electrode plate and the negative electrode plate. The
power-generating element includes a reaction area where a chemical
reaction associated with the charge and discharge occurs. The
plurality of protruding portions have a first protruding portion in
contact with a first area in the case and a second protruding
portion in contact with a second area in the case. The first area
in the case is opposite to the reaction area, and the second area
in the case is opposite to the area of the power-generating element
except the reaction area.
According to the present invention, the first protruding portion
can be used to give the restraint force only to the reaction area.
The restraint force can be given only to the reaction area to
equalize the restraint forces applied to the reaction areas of the
plurality of electric storage elements. The second protruding
portion can be used to give the restraint force to the entire case
including the first are and the second area, thereby preventing the
restraint force from being applied only to part of the case (first
area).
The first area can be defined as an area opposite to an area of the
plurality of electric storage elements where the reaction areas are
overlapped one another in the predetermined direction. The second
area can be defined as an area not opposite to any of the reaction
areas in the plurality of electric storage elements.
The positive electrode plate can be formed of a positive electrode
collector plate and a positive electrode active material layer
formed on the positive electrode collector plate, and the negative
electrode plate can be formed of a negative electrode collector
plate and a negative electrode active material layer formed on the
negative electrode collector plate. The separator can be larger in
width than the positive electrode active material layer and the
negative electrode active material layer. With this configuration,
if the separator is displaced from the positive electrode active
material layer or the negative electrode active material layer, the
separator can be interposed between the positive electrode active
material layer and the negative electrode active material
layer.
The second protruding portion can give the restraint force to an
edge of the separator through the case. The separator can be
contracted, for example due to heat production in the
power-generating element associated with charge and discharge. The
contraction of the separator can be prevented by using the second
protruding portion to give the restraint force to the edge of the
separator.
When the plurality of first protruding portions are provided on the
restraint place, at least one of the first protruding portions can
be placed along an edge of the first area. This allows the
placement of the first protruding portions with the efficient use
of the first area. When the plurality of second protruding portions
are provided on the restraint plate, at least one of the second
protruding portions can be placed along an edge of the second area.
This allows the placement of the second protruding portions with
the efficient use of the second area.
The power-generating element can be provided by winding the
positive electrode plate, the negative electrode plate, and the
separator around a predetermined axis. At least one of the first
protruding portion and the second protruding portion can extend in
a direction orthogonal to the direction in which the predetermined
axis extends, in a plane including the first area and the second
area. The length of the case in the direction in which the
predetermined axis extends can be larger than the length of the
case in the direction orthogonal to the predetermined axis in the
plane including the first area and the second area.
A structure for giving the restraint force to the electric storage
elements can be provided by using a pair of end plates and a
coupling member. The pair of end plates can be placed at the
positions where the plurality of electric storage elements are
sandwiched in the predetermined direction. The coupling member can
extend in the predetermined direction and can be fixed to the pair
of end plates. This can shift the pair of end plates in a direction
in which they are brought closer to each other to give the
restraint force to the electric storage element.
The space formed by the protruding portion on the restraint plate
can be used as a path in which a heat exchange medium for use in
adjusting the temperature of the electric storage element is moved.
When the electric storage element produces heat, a heat exchange
medium for cooling can be used. When the electric storage element
is cooled, a heat exchange medium for heating can be used. This can
maintain the temperature of the electric storage element within a
predetermined temperature range to suppress a reduction in
input/output characteristics of the electric storage element.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 An external view of a battery stack.
FIG. 2 An external view of a cell.
FIG. 3 A diagram showing the internal structure of the cell.
FIG. 4 A developed view of a power-generating element.
FIG. 5 An external view of the power-generating element.
FIG. 6 A diagram for explaining a reaction area of the
power-generating element.
FIG. 7 A front view of a restraint plate.
FIG. 8 A side view of the restraint plate.
FIG. 9 A diagram for explaining the positions of a first protruding
portion and a second protruding portion with respect to the
power-generating element.
FIG. 10 A diagram for explaining the areas where the first
protruding portion and the second protruding portion are
placed.
FIG. 11 A diagram for explaining the contraction of a
separator.
FIG. 12 A diagram for explaining the contraction of the
separator.
FIG. 13 A front view of the restraint plate which is Modification
1.
FIG. 14 A front view of the restraint plate which is Modification
2.
FIG. 15A An external view of the first protruding portion and the
second protruding portion.
FIG. 15B An external view of the first protruding portion and the
second protruding portion in Modification 1.
FIG. 15C An external view of the first protruding portion and the
second protruding portion in Modification 2.
MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will hereinafter be
described.
Embodiment 1
Description is now made of a battery stack (corresponding to an
electric storage apparatus) which is Embodiment 1 of the present
invention with reference to FIG. 1. FIG. 1 is an external view of
the battery stack which is the present embodiment. In FIG. 1, an X
axis, a Y axis, and a Z axis are axes orthogonal to each other, and
the axis corresponding to a vertical direction is defined as the Z
axis in the present embodiment. The relationship between the X
axis, the Y axis, and the Z axis applies to the other figures.
The battery stack 1 shown in FIG. 1 can be mounted on a vehicle,
for example. Examples of the vehicle include a hybrid vehicle and
an electric vehicle. Such a vehicle can convert an electric energy
output from the battery stack 1 into a kinetic energy which is used
to run the vehicle. For mounting the battery stack 1 on the
vehicle, the battery stack 1 can be housed into a stack case.
The battery stack 1 has a plurality of cells (corresponding to
electric storage elements) 10, and the plurality of cells 10 are
arranged along the X direction. The number of the cells 10 can be
set as appropriate based on the output or the like required of the
battery stack 1. A secondary battery such as a nickel metal hydride
battery or a lithium-ion battery can be used as the cell 10. An
electric double layer capacitor may be used instead of the
secondary battery.
As shown in FIG. 2, the cell 10 has a battery case 11 which can be
made of metal, for example. The cell 10 is of a so-called square
type, and the battery case 11 of the square-type cell 10 has a
shape conforming to a rectangular parallelepiped. In the present
embodiment, the length of the battery case 11 in the Y direction is
larger than the length of the battery case 11 in the Z
direction.
The battery case 11 formed in this manner allows an increased size
of the cell 10 (a power-generating element 15, later described)
while reducing the height (length in the Z direction) of the cell
10. The reduced height of the cell 10 facilitates the mounting of
the battery stack 1 on the vehicle. In addition, a lid 11b, later
described, can be increased in size to allow the smooth attachment
of parts (a valve 12, a positive electrode terminal 13, and a
negative electrode terminal 14, later described) to the lid
11b.
As shown in FIG. 3, the battery case 11 houses the power-generating
element 15. The battery case 11 has a case body 11a and the lid
11b. The case body 11a has an opening portion for incorporating the
power-generating element 15, and the lid 11b closes the opening
portion of the case body 11a. This hermetically seals the battery
case 11. The lid 11b and the case body 11a can be fixed by welding,
for example.
As shown in FIG. 2, the valve 12 is provided in the lid 11b. When
gas is produced within the battery case 11, the valve 12 is used to
let out the gas to the outside of the battery case 11.
Specifically, when the produced gas increases the internal pressure
of the battery case 11 to the operating pressure of the valve 12,
the valve 12 is changed from a closed state to an open state to let
out the gas to the outside of the battery case 11.
The positive electrode terminal 13 and the negative electrode
terminal 14 are fixed to the lid 11b. The positive electrode
terminal 13 is connected to the power-generating element 15 through
a positive electrode tab 16a, and the negative electrode terminal
14 is connected to the power-generating element 15 through a
negative electrode tab 16b. The positive electrode terminal 13
extends through the lid 11b, and has a portion protruding outside
the battery case 11 and a portion protruding into the battery case
11. The negative electrode terminal 14 extends through the lid 11b,
and has a portion protruding outside the battery case 11 and a
portion protruding into the battery case 11.
FIG. 4 is a developed view of the power-generating element 15. The
power-generating element 15 has a positive electrode plate 151, a
negative electrode plate 152, and a separator 153. The positive
electrode plate 151 has a positive electrode collector plate 151a
and a positive electrode active material layer 151b formed on a
surface of the positive electrode collector plate 151a. The
positive electrode active material layer 151b includes a positive
electrode active material, a conductive agent, a binder and the
like. The positive electrode active material layer 151b is formed
on a region of the positive electrode collector plate 151a such
that the remaining region of the positive electrode collector plate
151a is exposed. The positive electrode active material layer 151b
can be formed on the surface of the positive electrode collector
plate 151a by using an application apparatus such as a gravure
coater or a die coater.
The negative electrode plate 152 has a negative electrode collector
plate 152a and a negative electrode active material layer 152b
formed on a surface of the negative electrode collector plate 152a.
The negative electrode active material layer 152b includes a
negative electrode active material, a conductive agent, a binder
and the like. The negative electrode active material layer 152b is
formed on a region of the negative electrode collector plate 152a
such that the remaining region of the negative electrode collector
plate 152a is exposed. The negative electrode active material layer
152b can be formed on the surface of the negative electrode
collector plate 152a by using an application apparatus such as a
gravure coater or a die coater. The positive electrode active
material layer 151b, the negative electrode active material layer
152b, and the separator 153 are impregnated with an electrolytic
solution.
The positive electrode plate 151, the negative electrode plate 152,
and the separator 153 are stacked in the order shown in FIG. 4 and
the stack is wound in a direction indicated by an arrow R in FIG. 5
to provide the power-generating element 15. The stack is wound
under tension around an axis AXL extending in the Y direction. The
edge of the winding can be fastened, for example with a tape. The
stack wound around the axis AXL is deformed into a shape conforming
to the battery case 11 so that the stack can be housed in the
battery case 11.
In FIG. 5, at one end of the power-generating element 15 in the Y
direction, only the positive electrode collector plate 151a is
wound. The positive electrode tab 16a (see FIG. 3) is fixed to that
positive electrode collector plate 151a. As shown in FIG. 3, one
end of the positive electrode tab 16a is connected to the positive
electrode terminal 13, and the other end of the positive electrode
tab 16a is connected to the power-generating element 15 (positive
electrode collector plate 151a). The positive electrode terminal 13
and the positive electrode tab 16a may be formed integrally.
In FIG. 5, at the other end of the power-generating element 15 in
the Y direction, only the negative electrode collector plate 152a
is wound. The negative electrode tab 16b (see FIG. 3) is fixed to
that negative electrode collector plate 152a. As shown in FIG. 3,
one end of the negative electrode tab 16b is connected to the
negative electrode terminal 14, and the other end of the negative
electrode tab 16b is connected to the power-generating element 15
(negative electrode collector plate 152a). The negative electrode
terminal 14 and the negative electrode tab 16b may be formed
integrally.
An area (referred to as a reaction area) Ar shown in FIG. 3 and
FIG. 5 refers to the areas of the positive electrode active
material layer 151b and the negative electrode active material
layer 152b that are opposed to each other with the separator 153
interposed therebetween. A chemical reaction occurs in the reaction
area Ar when the cell 10 (power-generating element 15) is charged
or discharged. For example, in the charge of the lithium-ion
secondary battery serving as the cell 10, lithium ions and
electrons are released from the positive electrode active material
layer 151b and absorbed by the negative electrode active material
layer 152b. In the discharge of the lithium-ion secondary battery,
the reaction reverse to that in the charge occurs in the positive
electrode active material layer 151b and the negative electrode
active material layer 152b.
FIG. 6 is a diagram showing the positional relationship between the
positive electrode plate 151, the negative electrode plate 152, and
the separator 153. The reaction area Ar refers to the areas of the
positive electrode active material layer 151b and the negative
electrode active material layer 152b that are overlapped to each
other with the separator 153 interposed therebetween. The reaction
area Ar has a width of W.sub.A in the Y direction. Since the
positive electrode active material layer 151b has the smallest
length (width) in the Y direction in the present embodiment, the
width W.sub.A of the reaction area Ar corresponds to the width of
the positive electrode active material layer 151b.
In FIG. 6, W.sub.B represents the length (width) of the negative
electrode active material layer 152b in the Y direction, and the
width W.sub.B is larger than the width W.sub.A. W.sub.C represents
the length (width) of the separator 153 in the Y direction, and the
width W.sub.C is larger than the width W.sub.B. Since the width
W.sub.C of the separator 153 is larger than the width W.sub.A of
the positive electrode active material layer 151b and the width
W.sub.B of the negative electrode active material layer 152b, both
end portions of the separator 153 in the Y direction protrude from
the positive electrode active material layer 151b and the negative
electrode active material layer 152b.
The width W.sub.C of the separator 153 larger than the width
W.sub.A of the positive electrode active material layer 151b and
the width W.sub.B of the negative electrode active material layer
152b allows the separator 153 to be interposed between the positive
electrode active material layer 151b and the negative electrode
active material layer 152b. This can prevent any direct contact
between the positive electrode active material layer 151b and the
negative electrode active material layer 152b.
Although the reaction area Ar is defined by the positive electrode
active material layer 151b in the present embodiment, the present
invention is not limited thereto. If the width W.sub.B of the
negative electrode active material layer 152b is smaller than the
width W.sub.A of the positive electrode active material layer 151b,
the reaction area Ar is defined by the negative electrode active
material layer 152b. Thus, the width of the reaction area Ar
corresponds to the width W.sub.B of the negative electrode active
material layer 152b.
The plurality of cells 10 arranged along the X direction in the
battery stack 1 shown in FIG. 1 are connected electrically in
series. Specifically, the positive electrode terminal 13 of one of
the cells 10 is connected electrically to the negative electrode
terminal 14 of another one of the cells 10 through a bus bar. The
plurality of cells 10 may be connected electrically in parallel by
changing the shape or the like of the bus bar as appropriate.
The present embodiment employs two bus bar modules 20 for
electrically connecting the plurality of cells 10. Each of the bus
bar modules 20 has a plurality of bus bars and a resin plate
supporting the plurality of bus bars. The bus bar modules 20 can be
used to connect the plurality of bus bars easily to the plurality
of cells 10 (the positive electrode terminals 13 and the negative
electrode terminals 14).
A pair of end plates 31 are placed at both ends of the battery
stack 1 in the X direction. The pair of end plates 31 tightly hold
the plurality of cells 10 in the X direction. A band (corresponding
to a coupling member) 32 extends in the X direction and is fixed at
both ends to the pair of end plates 31. Fixing portions 32 provided
at both ends of the band 32 are fixed to the end plates 31. The
fixing of the end plates 31 to the fixing portions 32a is
performed, for example by fastening with bolts.
The band 32 can be made of metal, for example. In the present
embodiment, the two bands 32 are placed over an upper face of the
battery stack 1. Although not shown in FIG. 1, two bands 32 are
also placed over a lower face of the battery stack 1.
The bands 32 can be fixed to the pair of end plates 31 to give a
restraint force to the plurality of cells 10 constituting the
battery stack 1. The restraint force refers to a force which
tightly holds the plurality of cells 10 in the X direction. The
restraint force given to the cells 10 can reduce the expansion of
the cells 10, for example. In the lithium-ion secondary battery
serving as the cell 10, since the power-generating element 15 is
repeatedly expanded and contracted due to charge and discharge, the
restraint force given to the cells 10 can suppress a reduction in
input/output performance of the cells 10 (power-generating elements
15).
Although the present embodiment includes the two bands 32 placed
over the upper face of the battery stack 1 and the two bands 32
placed over the lower face of the battery stack 1, the present
invention is not limited thereto. The number of the bands 32 placed
over the upper face and the lower face of the battery stack 1 can
be set as appropriate. It is only required that the band 32 should
be fixed to the pair of end plates 31 to give the restraint force
to the cells 10. Alternatively, the band 32 may be replaced with a
structure for shifting the pair of end plates 31 in a direction in
which they are brought closer to each other. In this case, the
restraint force can also be given to the cells 10.
A restraint plate 40 is placed between two of the cells 10 adjacent
to each other in the X direction. The restraint plate 40 can be
made of an insulating material such as resin, for example. The
restraint plate 40 made of the insulating material can be used to
provide insulation between the two cells 10 adjacent in the X
direction.
FIG. 7 is a diagram of the restraint plate 40 viewed from the X
direction, that is, a diagram (front view) of the restraint plate
40 when viewed from the cell 10. FIG. 8 is a sectional view taken
along line Z1-Z1 in FIG. 7.
As shown in FIG. 7, the restraint plate 40 has a plurality of first
protruding portions 41 and two second protruding portions 42. The
first protruding portions 41 and the second protruding portions 42
are provided in the same plane (Y-Z plane) of the restraint plate
40 and protrude in the X direction. The plane of the restraint
plate 40 in which the first protruding portions 41 and the second
protruding portions 42 are provided is opposite to the cell 10 in
the X direction.
The first protruding portion 41 and the second protruding portion
42 extend in the Z direction. In other words, the first protruding
portion 41 and the second protruding portion 42 extend in the
direction (Z direction) orthogonal to the direction (Y direction)
in which the axis AXL (see FIG. 5) of the power-generating element
15 extends in the Y-Z plane.
The plurality of first protruding portions 41 are arranged along
the Y direction. The two second protruding portions 42 are placed
at the positions between which the plurality of first protruding
portions 41 are sandwiched in the Y direction. In other words, the
second protruding portions 42 are located closer to the outer edges
of the restraint plate 40 than the first protruding portions 41 in
the Y direction. The number of the first protruding portions 41 can
be set as appropriate. The interval between two of the first
protruding portions 41 adjacent in the Y direction can be set as
appropriate.
As shown in FIG. 8, the first protruding portions 41 and the second
protruding portions 42 are formed on only one of the faces of the
restraint plate 40 in the X direction, and the other face of the
restraint plate 40 is formed of a flat surface. In other words, in
the configuration in which the restraint plate 40 is sandwiched
between two cells 10 (the configuration shown in FIG. 8), the first
protruding portions 41 and the second protruding portions 42 are
formed only on the face of the restraint plate 40 opposite to one
of those cells 10. The first protruding portions 41 and the second
protruding portions 42 are not formed on the face of the restraint
plate 40 opposite to the other cell 10. Alternatively, the first
protruding portions 41 and the second protruding portions 42 may be
formed on the face of the restraint plate 40 opposite to the other
cell 10.
The end faces of the first protruding portions 41 and the second
protruding portions 42 are in contact with the cell 10 (battery
case 11) to form spaces S (see FIG. 7) between the restraint plate
40 and the cell 10. The space S is formed between two of the first
protruding portions 41 adjacent in the Y direction. The space S
serves as a space where air (corresponding to a heat exchange
medium) moves for adjusting the temperature of the cell 10. The air
for adjusting the temperature of the cell 10 can also be passed in
a space formed between the first protruding portion 41 and the
second protruding portion 42 adjacent in the Y direction.
When the cell 10 produces heat, air for cooling can be directed to
the space S to suppress an increase in temperature of the cell 10.
When the cell 10 is extremely cooled, air for heating can be
directed to the space S to suppress a reduction in temperature of
the cell 10. The temperature of the cell 10 can be maintained
within a desired temperature range to prevent any deterioration of
the input/output characteristics of the cell 10.
As shown in FIG. 7, the first protruding portion 41 extends in the
Z direction to cause the air for temperature adjustment to flow in
the Z direction along the first protruding portion 41. The length
of the battery case 11 in the Z direction is smaller than the
length of the battery case 11 in the Y direction. Thus, the passage
of the air for temperature adjustment in the Z direction is
preferable to the passage of the air for temperature adjustment in
the Y direction.
If the air flow path is increased in length, the heat exchange in
the upstream section may be likely to affect the downstream section
to produce temperature variations along the air movement direction.
Specifically, if the air is passed in the Y direction, the
temperature may vary depending on the position in the Y direction
within the cell 10. In contrast, the shorter air flow path can
efficiently achieve the temperature adjustment for the cells 10 to
suppress the temperature variations along the air movement
direction.
When the air for temperature adjustment is supplied from the upper
face of the battery stack 1, the air flows along the restraint
plate 40 from top to bottom. During the movement of the air in the
space S, heat exchange can be performed between the air and the
cell 10 to adjust the temperature of the cell 10. The air after the
temperature adjustment is let out through the lower face of the
battery stack 1. On the other hand, when the air for temperature
adjustment is supplied from the lower face of the battery stack 1,
the air flows along the restraint plate 40 from bottom to top. The
air after the temperature adjustment is let out through the upper
face of the battery stack 1.
Although the air is used to adjust the temperature of the cell 10
in the present embodiment, the present invention is not limited
thereto. A gas other than the air or a liquid can be used. When the
liquid is used, an insulating one is preferably used. For the
liquid, the path for moving the liquid needs to be hermetically
sealed.
Next, description is made of the positions to provide the first
protruding portions 41 and the second protruding portions 42. FIG.
9 is a diagram for explaining the positions of the first protruding
portions 41 and the second protruding portions 42 with respect to
the power-generating element 15. As shown in FIG. 9, the outer face
of the power-generating element 15 is almost covered with the
separator 153, and the positive electrode collector plate 151a and
the negative electrode collector plate 152a are exposed at both
ends of the power-generating element 15 in the Y direction. When
the battery case 11 is omitted, the first protruding portions 41
and the second protruding portions 42 are placed at the positions
shown in FIG. 9 with respect to the power-generating element
15.
The plurality of first protruding portions 41 are placed in a first
area A1 and are used to give the restraint force to the reaction
area Ar of the power-generating element 15. In the configuration
shown in FIG. 9, two of the first protruding portions 41 are placed
along the edges of the first area A1. The ends of the first
protruding portions 41 are in contact with the area of the battery
case 11 that corresponds to the first area A1.
The second protruding portions 42 are placed in second areas A2. In
the configuration shown in FIG. 9, the second protruding portions
42 are placed along the edges of the second areas A2 and are placed
along the edges of the separator 153. The ends of the second
protruding portions 42 are in contact with the areas of the battery
case 11 that corresponds to the second areas A2. The areas of the
battery case 11 that correspond to the first area A1 and the second
area A2 are located in the same plane (Y-Z plane).
Since the plurality of cells 10 are arranged along the X direction
in the present embodiment, the cells 10 may be misaligned in
manufacturing the battery stack 1. Specifically, the cells 10 may
be displaced in the Y direction. The position variations between
the cells 10 cause position variations between the reaction areas
Ar of the power-generating elements 15 as shown in FIG. 10.
In the present embodiment, the first area A1 is set in view of the
position variations between the reaction areas Ar. Specifically, as
shown in FIG. 10, the first area A1 is defined as the area where
all the reaction areas Ar are overlapped one another. The first
area A1 is the area where all the reaction areas Ar are overlapped
one another when the battery stack 1 is viewed from the X
direction. The width of the first area A1 shown in FIG. 10
corresponds to the length in the Y direction.
The first area A1 can be determined by previously conducting an
experiment or the like to specify a maximum displacement Dmax found
when the reaction areas Ar are misaligned. The misalignment of the
reaction areas Ar to be considered is the displacement of the
reaction areas Ar in the Y direction (left-right direction in FIG.
10). The displacement Dmax can be determined on the basis of the
reaction area Ar displaced furthest to the left in FIG. 10 (second
row) and the reaction area Ar displaced furthest to the right in
FIG. 10 (third row).
Although the illustration in FIG. 10 considers the misalignment of
the reaction areas Ar resulting from the misalignment of the cells
10, the present invention is not limited thereto. The misalignment
of the reaction areas Ar may occur due to another factor.
In forming the positive electrode active material layer 151b on the
surface of the positive electrode collector plate 151a, the
positive electrode active material layer 151b may be displaced with
respect to the positive electrode collector plate 151a depending on
the characteristics of the application apparatus or the like. Since
the reaction area Ar is defined by the positive electrode active
material layer 151b in the present embodiment, the displacement of
the positive electrode active material layer 151b with respect to
the positive electrode collector plate 151a leads to the
displacement of the reaction area Ar. In forming the negative
electrode active material layer 152b on the surface of the negative
electrode collector plate 152a, the negative electrode active
material layer 152b may also be displaced with respect to the
negative electrode collector plate 152a depending on the
characteristics of the application apparatus or the like.
As described above, the power-generating element 15 is provided by
stacking the positive electrode plate 151, the negative electrode
plate 152, and the separator 153, and then winding the stack. The
positive electrode plate 151 (positive electrode active material
layer 151b) may be displaced in stacking the positive electrode
plate 151 or winding the positive electrode plate 151. The
displacement of the positive electrode active material layer 151b
causes the displacement of the reaction area Ar. The negative
electrode plate 152 (negative electrode active material layer 152b)
may be displaced in stacking the negative electrode plate 152 or
winding the negative electrode plate 152.
If the positive electrode active material layer 151b (reaction area
Ar) is displaced during the manufacture of the cell 10, the
resulting reaction area Ar is displaced even when the plurality of
cells 10 are located without displacement during the assembly of
the battery stack 1. The displacement of the reaction area Ar
occurs during the assembly of the battery stack 1 or the
manufacture of the cell 10, and is difficult to completely
eliminate. Thus, only the cells 10 having the displacement of the
reaction area Ar falling within an allowable range are used for the
battery stack 1.
In the present embodiment, the first protruding portions 41 placed
in the first area A1 can give the uniform restraint force to the
reaction areas Ar of all the cells 10 (power-generating elements
15). As shown in FIG. 10, since the first area A1 overlaps with all
the reaction areas Ar, the first protruding portions 41 placed in
the first area A1 can equalize the restraint loads transferred from
the first protruding portions 41 to the reaction areas Ar. This can
provide equal restraint conditions to achieve the same input/output
performance in all the cells 10.
If the first protruding portions 41 are placed in an area wider
than the first area A1, the restraint force given to the reaction
areas Ar may vary. Specifically, if the first protruding portion 41
is placed in an area outside the first area A1, one reaction area
Ar receives the restraint force from the first protruding portion
41 but another reaction area Ar does not receive the restraint
force. For example, when the first protruding portion 41 is placed
in the area outside the first area A1 in FIG. 10, the restraint
force from this first protruding portion 41 is given only to one of
the reaction areas Ar in the second and third rows.
If only the first protruding portions 41 are placed in the first
area A1, the restraint force is applied only to part of the cell 10
(battery case 11). The restraint force applied only to the first
area A1 in the battery case 11 easily deforms the area of the
battery case 11 except the first area A1. Since not only the first
area A1 but also other areas on the surface of the battery case 11
receive the restraint force, the application of the restraint force
only to the first area A1 deforms the other areas. When the battery
case 11 is deformed, the restraint load transferred from the first
protruding portion 41 to the power-generating element 15 is reduced
accordingly.
To address this, as shown in FIG. 9, the second protruding portions
42 are provided in the second areas A2 in the present embodiment.
The first protruding portion 41 and the second protruding portion
42 is not provided in the area located between the first area A1
and the second area A2. The second areas A2 are set in the area not
overlapped with any reaction area Ar in view of the displacement of
the reaction area Ar. Specifically, as shown in FIG. 10, the second
areas A2 are located outside the most displaced reaction areas Ar
(in the second and third rows).
The second protruding portions 42 placed in the second areas A2 can
give the restraint force also to the second area A2 in the battery
case 11. As a result, the restraint force can be given to the
entire face of the battery case 11 which receive the restraint
force, thereby giving the uniform restraint force to the entire
battery case 11. This can suppress the deformation of part of the
battery case 11 and thus prevent the reduction in restraint load
due to the deformation of the battery case 11.
Since the second area A2 is located outside the reaction area Ar,
the provision of the second protruding portion 42 in the second
area A2 can avoid the application of the restraint force from the
second protruding portion 42 to the reaction area Ar. In other
words, only the restraint force from the first protruding portion
41 is applied to the reaction area Ar to maintain the uniform
restraint force acting on all the reaction areas Ar.
When the first protruding portions 41 are placed only in the first
area A1, the restraint force is insufficiently applied to the edges
of the separator 153. In FIG. 9, the restraint force is
insufficiently applied to the edges of the separator 153 overlapped
with the second protruding portions 42.
Since the cell 10 (power-generating element 15) produces heat due
to charge and discharge, the heat may contract the separator 153.
If the restraint force is not applied to the edges of the separator
153, the contraction of the separator 153 displaces the edges of
the separator 153 as shown in FIG. 11 and FIG. 12. Specifically,
edges 153a and 153b of the separator 153 are displaced inwardly.
Since the separator 153 is wound under tension, it is easily
deformed in directions indicated by arrows D1 in FIG. 12 but is not
easily deformed in directions indicated by arrows D2.
When the edge 153a of the separator 153 is deformed as shown in
FIG. 11 and FIG. 12, an edge 151c (see FIG. 11) of the positive
electrode plate 151 may be opposed to the negative electrode plate
152 without interposing the separator 153. When the edge 153b of
the separator 153 is deformed as shown in FIG. 11 and FIG. 12, an
edge 152c (see FIG. 11) of the negative electrode plate 152 may be
opposed to the positive electrode plate 151 without interposing the
separator 153.
As shown in FIG. 6, the edges 153a and 153b of the separator 153
are positioned outside the reaction area Ar, so that the second
protruding portions 42 placed in the second areas A2 outside the
reaction area Ar can be used to give the restraint force to the
edges 153a and 153b of the separator 153. The restraint force given
to the edges 153a and 153b of the separator 153 can suppress the
deformation of the edges 153a and 153b as shown in FIG. 11 and FIG.
12.
The second protruding portions 42 placed in the second areas A2 can
give the restraint force to the edges 153a and 153b of the
separator 153 through the battery case 11. Thus, the second
protruding portions 42 may not be overlapped with the edges (153a
and 153b) of the separator 153 as shown in FIG. 9.
Although the second protruding portion 42 extends in the Z
direction in the present embodiment, the present invention is not
limited thereto. It is only required that the second protruding
portion 42 should be placed in the second area A2. For example, the
length of the second protruding portion 42 in the Z direction may
be smaller than the length of the second protruding portion 42
shown in FIG. 7. As shown in FIG. 12, the edges 153a and 153b of
the separator 153 are deformed most easily at the center in the Z
direction.
For this reason, the second protruding portions 42 may be provided
only at the positions where the edges 153a and 153b are easily
deformed. In this case, the length of the second protruding portion
42 in the Z direction can be smaller than the length of the second
protruding portion 42 shown in FIG. 7.
Although the first protruding portions 41 are placed over the
entire first area A1 in the present embodiment, the present
invention is not limited thereto. It is only required that the
first protruding portions 41 should be placed in the first area A1,
and the positions of the first protruding portions 41 in the first
area A1 can be set as appropriate. For example, the first
protruding portions 41 can be placed only at the edges of the first
area A1 in the Y direction.
Although the second protruding portion 42 is placed in each of the
two second areas A2 shown in FIG. 9 and FIG. 10 in the present
embodiment, the present invention is not limited thereto.
Specifically, the second protruding portion 42 may be placed in
only one of the two second areas A2. In this case, the second
protruding portion 42 can also give the restraint force to the edge
of the separator 153 to suppress the deformation of the edge of the
separator 153.
Although the stack of the positive electrode plate 151, the
negative electrode plate 152, and the separator 153 is wound to
provide the power-generating element 15 in the present embodiment,
the present invention is not limited thereto. Specifically, the
power-generating element 15 may be provided only by stacking the
positive electrode plate 151, the negative electrode plate 152, and
the separator 153. The first area A1 and the second area A2 can be
defined for such a power-generating element 15 similarly to the
present embodiment, and the first protruding portion 41 can be
placed in the first area A1 and the second protruding portion 42
can be placed in the second area A2.
Although the first protruding portion 41 and the second protruding
portion 42 extend in the Z direction as shown in FIG. 7 in the
present embodiment, the shapes of the first protruding portion 41
and the second protruding portion 42 are not limited thereto. It is
only required that the first protruding portion 41 should be placed
in the first area A1 and the second protruding portion 42 should be
placed in the second area A2.
For example, the first protruding portions 41 and the second
protruding portions 42 can be provided as shown in FIG. 13 and FIG.
14. In the configuration shown in FIG. 13, the plurality of first
protruding portions 41 are arranged along the Z direction and the Y
direction in the first area A1. The plurality of second protruding
portions 42 are arranged along the Z direction in the second area
A2. The numbers of the first protruding portions 41 and the second
protruding portions 42 arranged along the Z direction can be set as
appropriate. Similarly, the number of the first protruding portions
41 arranged along the Y direction can be set as appropriate.
In the configuration shown in FIG. 14, the plurality of first
protruding portions 41 are arranged along the Y direction in the
first area A1. The plurality of first protruding portions 41 of one
row in an upper stage are shifted in the Y direction from the
plurality of first protruding portions 41 of one row in a lower
stage. Two second protruding portions 41 are arranged along the Z
direction in the second area A2. Columns (two columns) each
including the two second protruding portions 42 arranged along the
Z direction are shifted in the Z direction.
In the configurations shown in FIG. 13 and FIG. 14, the first
protruding portion 41 and the second protruding portion 14 can be
formed in any of shapes shown in FIG. 15A to FIG. 15C. FIG. 15A to
FIG. 15C show the examples of the outer shape of the first
protruding portion 41 (or the second protruding portion 42). In
FIG. 15A, the first protruding portion 41 (or the second protruding
portion 42) is formed in a rectangular parallelepiped. In FIG. 15B,
the first protruding portion 41 (or the second protruding portion
42) is formed in a cylinder. In FIG. 15C, the first protruding
portion 41 (or the second protruding portion 42) is formed in a
frustum of a cone.
When a protruding portion extending in the Y direction is provided
on the restraint plate 40, the displacement of the reaction areas
Ar does not need to be considered. If the reaction areas Ar are
displaced in the Y direction as shown in FIG. 10, the protruding
portion extending in the Y direction can be used to give the
uniform restraint force to all the reaction areas Ar. The
protruding portion extending in the Y direction is placed over both
the first area A1 and the second area A2. The present invention is
preferably used when the protruding portion (the first protruding
portion 41 and the second protruding portion 42) is provided for
each of the first area A1 and the second area A2.
The shapes of the first protruding portion 41 and the second
protruding portion 42 are not limited to the shapes shown in FIG.
15A to FIG. 15C. It is only required that the first protruding
portion 41 and the second protruding portion 42 should protrude in
the X direction.
* * * * *